Age-related dementia: risk halved by folates

In the elderly, the risk of dementia could be influenced by the level of folate (vitamin B9) in the blood, independent of that of other B vitamins and the diet followed. Specifically, those with higher concentrations of folate show a 50 percent lower risk of dementia than those with lower amounts. These data were obtained from a study of a population, the French, whose average folate consumption is quite low. The results suggest that supplementation with vitamin B9 might play a protective role in the brain when baseline blood folate levels are low.

The research was conducted by researchers at the University of Bordeaux (France) and published in the journal Nutrients.

Folic acid: an essential vitamin for health

Folic acid is a vitamin (vitamin B9) involved in many essential functions in the human body, including DNA synthesis. The term folic acid refers to the chemical molecule found in vitamin supplements or used in the food industry to enrich certain foods; while the term folate refers to a group of folic acid-like substances found in certain foods such as green leafy vegetables and citrus fruits. Folic acid and folates are indispensable for all cells in the body, particularly those that need to reproduce or renew themselves; for this reason, folic acid requirements increase greatly during pregnancy.

In addition to the periconceptional period, folic acid is also important for general health; in fact, deficiency of the vitamin causes a type of anemia, called megaloblastic anemia, and can promote increased levels of homocysteine levels, an amino acid that in high concentrations is associated with the risk of cardiovascular disease and heart attack. B vitamins, play a key role in central nervous system function and appear to have a promising role in the prevention of dementia and Alzheimer's disease..

Epidemiological studies have found associations between high intakes of B vitamins and a lower risk of dementia and Alzheimer's disease, particularly with regard to folate. However, the diet is often insufficient to ensure proper folate intake, and it is necessary to consume folic acid supplements or "fortified" foods to which this vitamin has been added. In some countries, such as Canada, it has been approved and is mandatory to produce certain foods with folic acid added. 

Nowadays, 78 countries in the world have activated mandatory folic acid fortification programs, whereas, many European Union member states have not implemented fortification. These include France where the study was conducted and where the population follows a diet low in folate, reporting low levels of vitamin B9 in the blood. In other countries with similar conditions to France, such as Italy, the Netherlands, and the United Kingdom, several studies have suggested that higher folic acid consumption could be linked to improved memory and dementia symptoms in older people.

Folate-rich diet reduces risk of dementia by 50%

Led by Sophie Lefèvre-Arbogast, a researcher at the University of Bordeaux, scientists evaluated the ability of certain food-introduced B vitamins to influence the risk of dementia in the French population. The team observed a strong association between folate consumption and the long-term risk of dementia; in particular, this was 50 percent lower in the elderly with the highest levels of vitamin B9 in the blood, compared to those with very low levels.

In contrast, no association was found for vitamins B6 and B12. Although these results are similar to those of other studies, they are in contrast to those shown in some epidemiological studies conducted in countries where mandatory fortification is in effect. According to the researchers, this discrepancy suggests that the brain-protective action of folate occurs in those who normally have a deficiency of the vitamin, while it may be ineffective in subjects who show higher basal blood concentrations of folate.

The details of the research

During the study, researchers analyzed data from 1,321 elderly people without dementia. Interviews with each participant were conducted at the beginning of the study to identify lifestyle and health-related socio-demographic characteristics, and neuro-psychological tests and specific blood tests were also conducted. 

All participants completed a food diary to define their usual diet, and were monitored for an average of 7.4 years. Statistical models used showed that higher folate intake was inversely associated with dementia risk, with a 50 percent lower risk for those with the highest folate concentration.

The protective role of folates is also confirmed by other studies

The data obtained showed that high folate intake is inversely associated with dementia risk, independent of that of other B vitamins and diet quality, according to the researchers. These findings are consistent with at least three previous studies conducted he United States, in which higher folate intake was found to be associated with a lower risk of dementia and Alzheimer's disease. The protective role of folic acid on dementia in populations with relatively low intakes, such as France, will need to be explored with future studies.

Source: Sophie Lefèvre-Arbogast, et al, "Dietary B Vitamins and a 10-Year Risk of Dementia in Older Persons" Nutrients, Volume 8, page 761